Method and apparatus for cleaning the interior of industrial vessels by using rotating nozzle heads

ABSTRACT

Industrial vessels are cleaned with fluids injected under pressure through rotating nozzle assemblies inserted at positions which take into account vessel symmetry and the location of drainage outlets. In a nozzle assembly, nozzles are distributed symmetrically in the nozzle head, and the nozzles are inclined to the axis of the nozzle head so that each nozzle sprays fluid in a different direction. A gas nozzle is positioned below the rotating nozzle assemblies.

United States Patent McDermott 1 Dec. 24, 1974 [54] METHOD AND APPARATUSFOR 2,443,721 6/1948 Butcher, Jr. 134 24 L G HE INTERIOR 0 3,001,5339/1961 Holdren 134/166 R 3,046,163 7/1962 Kearney et al.... 134/30 XINDUSTRIAL VESSELS BY USING 3,067,069 12/1962 Stack 134/30 X ROTATINGNOZZLE HEADS 3,142,306 7/1964 BOkZl, .lr 134/166 R [75] Inventor: DavidC. McDermott, Houston, Tex. E a] 2 3 yon [73] Assignee: Shell OilCompany, Houston, Tex. [22] Filed: Oct. 11, 1972 Primary Examiner-S.Leon Bashore Assistant Examiner-Richard V. Fisher [21] Appl. No.:296,714

[57] ABSTRACT [52] US Cl 134/24 Industrial vessels are cleaned withfluids injected [51] Int Cl Bosh 9/08 under pressure through rotatingnozzle assemblies in- [58] Fie'ld 36 40 9 4 serted at positions whichtake into account vessel sym- 134/98 99 167 R 22 R- 1 7 metry and thelocation of drainage outlets. In a nozzle assembly, nozzles aredistributed symmetrically in the he nozzles are inclined to the axis of[56] References Cited nozze head and t the nozzle head so that eachnozzle sprays fluid in a UNITED STATES PATENTS different direction. Agas nozzle is positioned below 1,624,865 4/1927 Freel 134/167 R therotating n le assemblies 1,816,954 8/1931 Byerley 134/30 UX 2,045,752 6/1936 Butterworth 134/24 X 7 Claims, 2 Drawing Figures Z i 1 1 1 1 j /K 7,1 n H A 4 I 1 I 1 12 1 -11 f 1 6;;1 I

METHOD AND APPARATUS FOR CLEANING THE INTERIOR OF INDUSTRIAL VESSELS BYUSING ROTATING NOZZLE HEADS BACKGROUND OF THE INVENTION It is well knownthat in-plant tank car cleaning can vastly improve the utilization oftank cars because the intrinsic inefficiency due to random demand can bereduced by increasing the number of cars in multiple service, and thiscan be achieved in many cases by routinely cleaning tank cars betweentrips, thus making them available for shipping any one of severalproducts on the next trip. Also, time-consuming activities can bechanged in order to reduce the total round-trip-time for each tank car.Thus, an example is the elimination of the travelling time to and from acontractors cleaning plant by carrying out tank car cleaning at themanufacturers shipping point.

If cleaning is to be carried out in the plant, such a method mustsatisfy at least two criteria. That is, the method must be rapid so thatsingle-spot cleaning centers on small areas of land can handle largenumbers of tank cars; and the quantity of effluent resulting from thecleaning operation must be small so that the problem of disposal isminimized.

Unfortunately, present tank car cleaning generally achieves neither ofthese criteria. In addition, the problem is further complicated by amulti-product use of tank cars. Thus, present cleaning apparatus is notsufficiently diversified so that it can be used for cleaning differentproducts without making substantial changes in the apparatus.

The present invention overcomes the above described difficulties of theprior art, and provides a successful solution thereto, as will beapparent from the following description thereof.

SUMMARY OF THE INVENTION The primary purpose of this invention residesin providing a method and apparatus whereby multi-product tank cars canbe efficiently and economically cleaned of products for improvedutilization.

The above purpose has been achieved by using traditional cleaning fluidswith improved means and techniques for distributing them. All of thecleaning fluids are injected into tank cars from a single nozzleassembly lowered through a man-way. Resulting liquids are removedthrough the bottom outlet while resulting vapors are removed through theman-way. For this improved method, a new nozzle design is provided whichresults in cleaning which is faster, cheaper, and more efficient thanexisting methods. An important economic benefit resulting from rapidin-plant cleaning is the improved utilization of a tank car fleet.

The nozzle assembly of the invention, which drops through a man-way,includes two main parts combined into one unit: (I) at least one andpreferably a pair of rotating nozzle heads for producing high velocityliquid jets, and (2) a gas nozzle. Sufficient nozzles are provided tocover the entire tank wall surface and the rate of rotation of thenozzle head is adjusted so that each part of the tank wall preferablyreceives fresh cleaning fluid several times each minute. The axis ofrotation of the nozzle head generally coincides with the tank axis. Inthe case of gas nozzles used for air or for steam cleaning, the gasenters through a concentric supply line supplying the'nozzle assemblyand exits from a T- shaped nozzle set about parallel to the tank caraxis just above the floor of the tank car. A flow pattern is establishedwhich extends the length of the tank car so that gas is deflected byeach head and forced to return along the upper portion of the tank toexit finally via the manway.

Within the framework of the above described apparatus and method, thepresent invention not only solves the above mentioned problems of theprior art, but also achieves further significant advantages as will beapparent from the description of preferred embodiments following.

DESCRIPTION OF THE DRAWINGS FIG. 1 provides a schematic showingofcleaning fluid distribution within a tank car;

FIG. 2 discloses the dimensions of a nozzle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the presentinvention there are provided various techniques and apparatus forcleaning several types of products shipped by tank car. Such productsmay be divided into four groups: Oils which can be removed withdetergent solutions, waxes which can be removed with hot water, solventswhich can be removed by steam distillation, and other materials whichmust be removed in solution with a solvent. Alternatively. such productsmay be divided into four main classes including medium or highvapor-pressure products, waxes, oils, and other products. Medium or highvapor-pressure products can be removed by extracting the vapor from thecar, thereby causing further evaporation. In addition, the process forremoving such materials can be made more rapid by heating the product.The general group of liquids known as solvents falls into this classthat also includes water, which must always be removed as the final stepin the cleaning operation. The remaining materials which do not fallwithin the first three classes or groups includes low vapor pressureproducts such as glycerine and hexylene glycol.

If routine in-plant cleaning is carried out, tank cars used for productswithin each of the above four groups or classes can be used for multipleproduct service. Cars can also be changed from one service group toanother if necessary, but such service changes may require additionalcleaning procedures to those used within one group of products. All thecleaning fluids utilized in the present invention can be injected intothe tank car from a single-nozle assembly lowered through the manway.Resulting liquids are removed through the bottom outlet while resultingvapors are removed through the manway.

Most of the products in the above described categories can be removed bymeans of basic cleaning fluids such as heated or cold dry air, steam,hot water, hot water containing detergent, and solvents. Air is usedprimarily for distilling water as the final stage of the cleaningprocess. It is useful also for distilling materials other than waterwhich do not present a tire hazard. If air is used for waterdistillation, it must have low relative humidity, which can be achievedeither by heating ambient air of high humidity or by cooling and thenheating ambient air. If the tank car to be dried is warm as a result ofa prior cleaning operation, then air at ambient temperature can be used,but if the tank car is cold, heated air is used. Steam is used as adistillation medium for products other than water, and its use removesthe danger of fire or explosion provided care is taken to remove the airoriginally present in the tank car. The mixture of steam and vaporleaving the tank car may be conducted to a condensation column forrecovery of the product. Steam also provides an efficient means forheating products such as wax, prior to removal with water. Steam forthis purpose may be blown directly into the tank car, or can be passedthrough heating coils. Melted wax can be removed with hot water at atemperature above the melting point of the wax. No detergent or solventis necessary, which is convenient because the wax on freezing separatesfrom the water and can then be recovered and recycled. It is necessaryto use a detergent forremoving oils, since water alone is ineffective.The oil cannot easily be separated from detergent solution, but providedthe solution is used only for removing surface films of oil, it can bere-used many times. Many types of solvents, including water, areavailable for a wide variety of products, and each is chosen for theparticular case.

The distribution technique of the present invention transmits thecleaning fluid with the greatest possible efficiency to the productwhich is distributed over the walls of the tank car, and the used fluidwith its entrained product is then efficiently removed from the tankcar. This technique is conducted satisfactorily with the system shownschematically in FIG. 1. The nozzle assembly 1, which drops in throughthe manway 2 of the tank car 3, includes two main parts, combined intoone unit: (I) a pair of rotatable nozzle heads 4 for producing highvelocity liquid jets and (2) a gas nozzle 5. Concentric supply pipes 6provide liquid and gas for the respective nozzles.

The rotating nozzle heads 4 are used for water, detergent, or solvent.In order to limit incoming fluid volumes to available outflow capacity,no attempt is made to cover the entire surface area of the tankcontinuously. Instead, as the nozzle head rotates, each nozzle covers aband 7 of the tank approximately 3 feet long. Sufficient nozzles areprovided to cover the entire tank wall surface and the rate of rotationof the nozzle head is such that each part of the tank wall preferablyreceives fresh cleaning fluid several times each minute. The axis ofrotation of the nozzle heads approximately coincides with the tank axis.Fluid from the jets sweeps over the tank car walls and runs down to thebottom of the tank where it drains toward the center and exits throughthe bottom outlet 8. Because the jet angles are oblique with respect tothe tank car wall, except at the heads of the tank, there is generally acomponent of the flow parallel to the surface causing a sweeping action.

The gas nozzle is used for air for drying or for steam for distillation.The gas enters through the concentric supply line 6 supplying the nozzleassembly and exits from a T-shaped nozzle set parallel to the tank caraxis just above the floor of the car. The gas exiting from the nozzlesets up a flow pattern which efficiently sweeps the tank car walls. Theflow extends the full length of the car and the gas is deflected by eachhead 9 and is forced to return via the upper portion of the tank to exitfinally via the manway 2.

Vapors are extracted from the manway by means of fans or other vapormoving equipment (not shown) and released to the atmosphere or divertedto a condensation column (not shown). Liquids are extracted from thebottom outlet 8 and pumped back to a holding tank (not shown), to asettling tank (not shown), or to waste. Recirculation of the cleaningfluids may be carried out to reduce the quantities of cleaning fluidsused and to reduce the volume of effluent. Both air drying and steamdistillation require evaporating a fluid offthe tank car interior bycirculating air or steam through the tank. By manifolcling the steam andair outside the tank car, the same inlet piping and nozzle can be usedfor drying and for steam distillation. The nozzle is inserted into themanway as an integral part of the nozzle assembly described hereinafter.Air and/or steam is directed toward both ends of the car from thecentral location.

The head 10 of the nozzle 5 is limited to a length of about 15 inches inorder to pass through a typical manway. Each half of the tee head shouldbe a minimum of about 2 diameters in length in order to effectivelydirect the jet issuing from the nozzle. This allows the nozzle exitdiameter to be a maximum of about 4 inches. Smaller nozzle exitdiameters result in too rapid a temperature drop after the air leavesthe nozzle, so the maximum diameter of 4 inches is preferred.

The riser 11 passes through the nozzle head assembly 4 and out themanway. The distance from the tee head 10 to the nozzle head assembly 4is adjustable in order for the tee to be placed at the proper height incars of varying diameter. The precise height of the tee above the tankcar floor is not critical so long as it is within the range of about 4to 8 inches from the tank car bottom.

The technique according to the present invention for cleaning wax carsincludes a steam soak which is long enough to melt the wax followed bywashing the walls with hot water at a temperature above the wax meltingpoint. Washing the walls is accomplished by inserting a rotating nozzleassembly into the car through the manway. Nozzles suitably arranged on arotating head direct streams of water to the entire car interior. Theimpact of the water jet on the walls and the subsequent rapid drainageof the hot water down the walls transports the wax out of the car in ashorter time than required for the unaided gravity drainage of moltenwax.

With the addition of detergent to hot water supply, the system abovedescribed for wax cars can be used for oil cars. The addition ofdetergent is accomplished using a manifold system located at the hotwater supply so that all of the equipment involved in placing therotating nozzle head into the car is the same for both oil and wax cars.The nozzle head design described heereinafter is suitable for both waxand oil car cleaning.

The rotating nozzle head 4 is in the form of a spherical sector; thisshape is chosen to provide a large surface area for mounting the nozzleswhile still allowing a clear region between nozzles. The body 12supports a rotating head 4 on each side and contains a drive mechanism(not shown) for the heads. As above noted, the supply pipes 6 whichextend down through the tank car manway hold the nozzle assembly on itslower end and contains piping (not shown) which supplies cleaning fluidto the heads. The support member also contains a pipeline (not shown)which passes through the body of the water nozzle assembly down to theair/- steam nozzle near the car bottom. The nozzle heads may be rotatedeither hydraulically or mechanically. A

rotational speed of at least about rpm is preferred and a supplypressure of about 250 psi is suitable.

The nozzle of this invention is designed to throw an effective stream ofwater the distance necessary to clean a large 24.000 gallon capacitycar. The interior shape of the nozzle is chosen so that the fluidvelocity is increased by reducing the cross-sectional area while at thesame time a minimum amount of additional turbulence is introduced intothe fluid. It is the turbulence which eventually destroys the stream offluid once it is outside the physical confines of the nozzle. Tominimize the turbulence, the inside of the nozzle has no protuberances,such as a gasket, and has a smooth surface finish.

The nozzle interior is shown in FIG. 2. All internal fillets have aradius of at least about nozzle diameters (d The preferred value of theexit diameter, d, is 3/ l6'inch. If internal fillet radii of about 4inches are used (21.3 d), the internal nozzle length is about 2% inches.

I claim as my invention:

1. A method for cleaning the interior of a tank car comprising:

inserting within the tank car interior a nozzle assembly including apair of rotatable nozzle heads for producing high velocity liquid jetsof cleaning fluid and a tee-shaped gas nozzle, the liquid nozzle headsand the gas nozzle being mounted on concentric supply pipes which supplyliquid to the rotatable nozzles and gas to the gas nozzle, the liquidnozzle heads generally coinciding with the tank axis, and the gas nozzlebeing parallel to the tank car axis just above the floor of the tankcar;

rotating the liquid nozzle heads at least about 10 rpm for producingliquid jets about an axis generally coinciding'with the tank axis so asto obliquely sweep a circumferential area approximately 3 feet long ofthe tank car wall with each nozzle so that each part of the tank wallreceives a sweeping action of fresh cleaning fluid several times eachminute continuously removing the liquid from a bottom outlet of the tankcar; and

establishing a gas flow pattern from the tee-shaped gas nozzle whichextends the length of the tank car so that gas is deflected by each headof the tank car and returned via the upper portion of the tank car toexit via a manway, the gas nozzle comprising a cylindrical head havingopposing nozzles with exit diameters not more than about 4 inches andthe length of each half of the head being a minimum of about twodiameters of the head in order to effectively direct the gas jetsissuing from the nozzles.

2. The method of claim 1 wherein liquid is supplied to the liquid nozzleheads at about 250 psi.

3. In combination with a tank car, a nozzle assembly for cleaning theinterior of the tank car comprising: a riser passing through a manwayand into the interior of the tank car,

at least one rotatable nozzle head, in communication with the riser, forproducing high velocity liquid jets from multiple nozzles positioned inthe head to liquid sweep substantially all of the tank car interior, theaxis of rotation of the nozzle head generally coinciding with thelongitudinal tank axis;

at least three nozzles distributed both circumferentially andlongitudinally in the nozzle head, so that both radial and longitudinaldistances between nozzles are constant, and the nozzles are inclined tothe axis of the nozzle head so that each nozzle sprays fluid in adifferent direction, the nozzles having internal fillets of at leastabout 20 nozzle exit diameters; tee-shaped gas nozzle positioned belowthe rotatable nozzle head and set about parallel to the tank car axisjust above the floor of the tank car to gas sweep substantially all ofthe tank car interior, comprising a cylindrical head having opposingnozzles with exit diameters not more than about 4 inches, the head beingin commmunication with the riser, and the length of each half of thehead being a minimum of about two diameters of the head in order toeffectively direct the jets issuing from the nozzles; and

concentric supply pipes which supply liquid to the rotatable nozzle headand gas to the gas nozzle.

4. The apparatus of claim 3 wherein the nozzle exit diameter is about3/16 inch.

5. The apparatus of claim 3 wherein the fillet radii are about 4 inchesand the internal nozzle length is about 2 /2 inches.

6. The apparatus of claim 3 wherein the rotatable head is in the form ofa spherical sector.

7. The apparatus of claim 6 wherein two rotatable heads are mounted onopposite sides of a drive mechanism for the heads.

1. A METHOD FOR CLEANING THE INTERIOR OF A TANK CAR COMPRISING:INSERTING WITHIN THE TANK CAR INTERIOR A NOZZLE ASSEMBLY ICLUDING A PAIROF ROTATABLE NOZZLE HEADS FOR PRODUCING HIGH VELOCITY LIQUID JETS OFCLEANING FLUID AND A TEE-SHAPED GAS NOZZLE, THE LIQUIF NOZZLE HEADS ANDTHE GAS NOZZLE BEING MOUNTED ON CONCENTRIC SUPPLY PIPES WHICH SUPPLYLIQUID TO THE ROTATABLE NOZZLES AND GAS TO THE GAS NOZZLE TE LIQUIDNOZZLE HEADS GENERALLY COINCIDING WITH THE TANK AXIS, AND THE GAS NOZZLEBEING PARALLEL TO THE TANK CAR AXIS JUST AOVE THE FLOOR OF THE TANK;ROTATING THE LIQUID NOZZLE HEADS AT LEAST ABOUT 10 RPM FOR PRODUCINGLIQUID JETS ABOUT AN AXIS GENERALLY COINCIDING WITH THE TANK AXIS SO ASTO OBLIQUELY SWEEP A CIRCUMFERENTIAL AREA APPROXIMATELY 3 FEET LONG OFTHE TANK CAR WALL WITH EACH NOZZLE SO THAT EACH PART OF THE TANK WALLRECIEVES A SWEEPING ACTION OF FRESH CLEANING FLUID SEVERAL
 2. The methodof claim 1 wherein liquid is supplied to the liquid nozzle heads atabout 250 psi.
 3. In combination with a tank car, a nozzle assembly forcleaning the interior of the tank car comprising: a riser passingthrough a manway and into the interior of the tank car, at least onerotatable nozzle head, in communication with the riser, for producinghigh velocity liquid jets from multiple nozzles positioned in the headto liquid sweep substantially all of the tank car interior, the axis ofrotation of the nozzle head generally coinciding with the longitudinaltank axis; at least three nozzles distributed both circumferentially andlongitudinally in the nozzle head, so that both radial and longitudinaldistances between nozzles are constant, and the nozzles are inclined tothe axis of the nozzle head so that each nozzle sprays fluid in adifferent direction, the nozzles having internal fillets of at leastabout 20 nozzle exit diameters; a tee-shaped gas nozzle positioned belowthe rotatable nozzle head and set about parallel to the tank car axisjust above the floor of the tank car to gas sweep substantially all ofthe tank car interior, comprising a cylindrical head having opposingnozzles with exit diameters not more than about 4 inches, the head beingin commmunication with the riser, and the length of each half of thehead being a minimum of about two diameters of the head in order toeffectively direct the jets issuing from the nozzles; and concentricsupply pipes which supply liquid to the rotatable nozzle head and gas tothe gas nozzle.
 4. The apparatus of claim 3 wherein the nozzle exitdiameter is about 3/16 inch.
 5. The apparatus of claim 3 wherein thefillet radii are about 4 inches and the internal nozzle length is about2 1/2 inches.
 6. The apparatus of claim 3 wherein the rotatable head isin the form of a spherical sector.
 7. The apparatus of claim 6 whereintwo rotatable heads are mounted on opposite sides of a drive mechanismfor the heads.